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The Impact of the Consumption of Tea on Iron Absorption

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 1st International Conference on Transformative Applied Research Proceedings
31st January 2025, NSBM Green University, Homagama, Sri Lanka

The Impact of the Consumption of Tea on Iron

Absorption
L.S.D. Perera1, R.M.D.S. Rathnayake1 and D. Dahanayake1*
1Department of Life Sciences, NSBM Green University, Sri Lanka
Corresponding Author E-mail: damayanthi.d@nsbm.ac.lk

Abstract—One of the most significant trace elements on -3-gallate,epigallocatechin, epicatechin-3-gallate, and

the planet is iron. Iron is a crucial ingredient for several epicatechin [4]. Additionally, black tea contains
biological processes, including energy metabolism, cell polymerized catechins such as theaflavins and
division, immunity, and oxygen transport. Iron is thearubigins [4]. These tea polyphenols have a strong
abundant yet frequently poorly accessible, particularly binding affinity to metal ions [4]. Therefore, it can
when it comes to the non-heme form that is present in cause to reduction in iron intake [4].
plant-based diets. The body absorbs heme iron, which
comes from animal sources, more easily. Tea serves as a The primary target of this effect is non-heme iron,
widely used beverage worldwide and includes especially when iron and tea are consumed at the same
polyphenols that might cease non-heme iron from being time [4]. However, drinking tea doesn’t affect the
absorbed by creating insoluble complexes in the body's capability to absorb heme iron from cooked
intestinal lumen. When iron-rich meals are eaten with meals [4]. This topic was chosen, because tea is widely
tea, this inhibitory impact is especially noticeable. consumed in several nations where iron shortage is a
However, drinking tea has minimal impact on the significant nutritional issue decided to embark on a
absorption of heme iron. Knowing how dietary elements formal investigation.
like tea affect iron absorption is important since iron
deficiency is common in many countries. Tea polyphenols II.METHODOLOGY
have been shown to limit iron absorption. However, these
effects can be lessened by implementing strategies
To explore the effects of tea consumption on iron
including drinking tea between meals and increasing absorption in the human body, a comprehensive review
dietary heme iron consumption. More scientific study is of literature from research articles, book chapters, and
required to further understand these relationships and research papers was conducted. The aim was to
create recommendations for people who may be synthesize current knowledge and identify trends in
susceptible to iron deficiency. This review aims to give an how tea impacts iron bioavailability. Sources were
idea about how the consumption of tea effects on iron selected based on their direct relevance to the question.
absorption in the human body. Research studies with Relevant databases, including PubMed, Google
clinical trials, book chapters, and review articles were Scholar, and ScienceDirect, were used with the
used to gather information. keywords such as “tea consumption,” “iron
KEYWORDS-enterocytes, heme iron, non-heme iron, absorption,” “iron bioavailability,” and “human
polyphenols, tea studies.”. Key information from each source was
extracted, focusing on the effects of tea consumption on
I.INTRODUCTION iron absorption in different populations, the
Iron is a vital component of our environment and is mechanisms by which tea affects iron bioavailability,
required by practically all kinds of life [1]. It is an and the findings from clinical trials.
essential metal for public health nutrition and a crucial
ingredient for the population [2]. It includes III.SIGNIFICANCE OF IRON
immunology, energy metabolism, proliferation, and Minerals are critical micronutrients that help the
differentiating cells, and circulation of oxygen [2]. In body's metabolic processes function properly [6].
the human body, iron is mostly found within Among the microminerals, iron is essential for many
complicated forms that are attached to proteins, physiological processes, including the formation of
including heme compounds including myoglobin or immune cells, oxidative metabolism, hemoglobin
hemoglobin, heme enzymes, and nonheme compounds synthesis, and electron transport media in cells. It also
like transferrin, ferritin, and flavin-iron enzymes [3]. helps to prevent anemia [6]. The most frequent forms
Most people drink tea, which is made from dried of iron in our diets are insoluble and poorly
Camellia sinensis leaves, all over the world [4]. Tea has bioavailable, despite being one of the metals that are
been shown to offer major health coverage as an anti- most abundant on our planet [7]. Less than 0.1% of the
inflammatory, antibacterial, anticarcinogenic, body's iron concentration is lost by humans daily, and
neurologically protective, cardiovascular, and this iron is supplied by dietary iron absorption [7].
potentially cholesterol-lowering diet [5]. Green tea and Iron deficiency can cause anemia, pale complexion,
black tea contain polyphenols such as epigallocatechin headaches, exhaustion or drowsiness, and reduced

ICTAR-2024-CMT-ID-39 34
 The Impact of the Consumption of Tea on Iron Absorption

resistance to infection [6]. Depending on age and developmental stage and the organism's iron status [9].
gender, 8 to 15 mg of iron should be consumed daily Since most of the dietary iron is in ferric form, it
[6]. Iron intake should be limited to 7–11 mg/day for demands to be turned into a ferrous form before being
children under the age of 13, 11 mg/day for males and utilized. So, the reduction process of food plays a key
15 mg/day for females in teens 14–18 years old, 8 role in iron absorption in the body [8]. Then,
mg/day for males and 18 mg/day for females in adults enterocytes should ingest ferrous iron through the
19–50 years old, and 8 mg/day for senior citizens over apical transporter [9]. Internalized iron is stored as
51 years old [6]. Consuming meals rich in iron minerals ferritin within enterocytes and subsequently transferred
is the only way to meet the body's requirements for iron, to the intestinal fluids by ferroproteins [9]. The
however, not all iron can be utilized due to differences circulatory system then carries iron in the type of
in component bioavailability [6]. transferrin-bound iron across the body [9].
IV.BIOAVAILABILITY OF IRON Heme with its globin molecule should be seen as a
powerful facilitator of iron intake since the ferrous iron
Heme iron and non-heme iron are the two types of included in the heme-globin particle is considerably
dietary iron [3]. The primary forms of heme iron are easier to absorb than non-heme iron [10]. Even while
derived from dietary meat, poultry, and fish, which heme iron makes up a lesser portion of the meal's
include hemoglobin and myoglobin [3]. Cereals, overall iron content, the fractional absorption is four to
pulses, legumes, fruits, and vegetables may contain six times higher [10]. In diets containing animal meat,
non-heme iron [3]. Iron-rich or fortified food such as roughly 10-15% of the dietary iron in the form of heme
iron-fortified cereals also contains non-heme iron [2]. is present [10].
Heme iron may account for more than 40% of the entire
intestinal iron absorption, because compared to non- About 20 – 30 % of heme iron is absorbed, making
heme iron, it is absorbed more easily, with an it extremely bioavailable [10]. 1–10% of non-heme iron
absorption rate of around 15 to 35% [2]. Because of is absorbed and it can be highly individual and greatly
non-heme iron absorption is influenced by other meal altered by facilitators or enhancers of iron absorption in
ingredients, it is significantly lower (2–20%) [3]. the meal [10]. Therefore, heme iron is known as "super
However, compared to heme iron, which is present in iron" for individuals who are in good health and
most meals, non-heme iron comprises a considerably "poisonous iron" for those who have hemochromatosis
greater fraction of the meal. Because of this, although [10].
non-heme iron has lower bioavailability than heme
While heme iron absorption is nearly consistent,
iron, it often provides more to iron nutriment [3]. The
non-heme iron bioavailability varies greatly [11]. It is
quantity of iron absorbed is greatly affected by the
usually considered that all non-heme dietary iron that
physical states of ferrous and ferric ions [2].
reaches the general iron pool in the gastrointestinal tract
Most of the non-heme iron in food arrives in the is taken in evenly, depending on the concentration of
ferric or oxidized form [2]. But enterocytes are more iron absorption amplifiers and inhibitors present in the
likely to carry ferrous iron [2]. At a pH of zero, ferrous foods and the individual's iron status [11].
iron is still soluble, but at pH values higher than three,
ferric iron precipitates [2]. Accordingly, ferric iron VI. INFLUENCE OF TEA ON IRON ABSORPTION
must be dissolved and chelated in the stomach before it Phenolic substances might affect the quantity of
can be absorbed in the less acidic duodenum [2]. The iron absorbed, with the combination of iron in the
other minerals in the meals swiftly complete chelation Bowel canal and the variation of intestinal permeability
as soon as the iron is issued in the intestinal lumen. [12]. Tannins are phenolic compounds that are included
These chelators may act as both enhancers and in tea and can lower iron bioaccessibility by creating
inhibitors of iron uptake through iron miscibility [2]. insoluble complexes inside the intestinal lumen [13].
Therefore, the composition of food is one of the The most significant problem with large amounts of
primary factors causing the absorption of non-heme tannin consumption is, it might reduce the iron
iron [2]. absorption from meals due to the presence of galloyl
groups in tannins [13].
V.ABSORPTION OF IRON TO THE GUT
Studies have stated that tea mainly inhibits the
The intestinal epithelium can utilize both heme and
intake of non-heme iron to a considerable scale by the
non-heme iron [8]. If there is minimal demand for iron,
development of insoluble iron complexes in the bowel
it shall be stored as ferritin in the enterocyte and will be
canal [14]. Black tea possesses a more inhibitive impact
released after numerous days, when the enterocytes are
on iron uptake even at low concentrations when
shed from the villus tip [8]. When iron is required by
compared with green tea due to its higher content of
the body, the iron carrier protein called ferroprotein
tannins [15]. When milk is added to tea, proteins in milk
allows it to cross the basolateral membrane and enter
bind to the flavonoids in tea [16]. But tea's iron
the bloodstream where it will bind to plasma transferrin
inhibitory properties are little or not affected by the
[8]. However, the process of heme iron absorption is
addition of milk [16]. But tea has no inhibitory effect if
limited in research work [8].
hemoglobin is cooked, because cooking can denature
In mammalians, iron absorption may vary due to the globins without affecting heme iron absorption
host-related and diet-related factors such as the [14].

35
 The Impact of the Consumption of Tea on Iron Absorption

Iron absorption from the reference diet ingested VII.CONCLUSION

with 1 cup of tea was lowered by 59%, whereas intake Tea, originating from dried Camellia sinensis
of 2 cups of tea with the reference diet reduced iron leaves, processed as green tea, black tea and oolong tea.
absorption by 67% [17], whereas a 1-hour gap between Tea polyphenols have a great affinity for proteins and
an iron-containing meal and tea drinking reduces the minerals, which may impact nutritional status. Phenolic
inhibitory effects on iron absorption [18]. Some studies compounds in tea are well known as possible inhibitors
show that tea consumption may not affect iron status of non-heme iron absorption. Phenolic substances
when people have enough iron storage [19]. There incorporate iron within the intestinal lumen, lowering
seems to be an adverse correlation between consuming iron bioaccessibility. Because of its greater tannin
tea and iron status, only among groups of persons with content, black tea has a more inhibitory effect on iron
borderline iron status [19]. absorption, even at low doses, than green tea. Tea's iron
It is reported that black tea polyphenols decrease inhibitory properties are little or not affected by adding
iron absorption on the meal by 62%, which is more than milk.
the inhibitory action of polyphenols from cocoa and In conclusion, chronic consumption of tea can
wine, due to the high titer of polyphenols with galloyl decrease intestinal penetrability, but it does not affect
groups [20]. Figure 1 includes the possible sites (A,B, iron intake if tea is not taken with a meal that contains
and C) in which iron can bind with the flavonoids such iron. There is limited evidence to prove the time
as catechins found in tea [11]. The complex formed is interval effect because previous studies were conducted
an unabsorbable iron complex that forms in the in animal models.
intestinal tract [11].
The formation of iron tannate complex is the major
It is claimed that a single iron attaches to three reason for to reduction of iron absorption. As a result,
catechol or galloyl groups, with a polyphenol: iron consuming tea after having a meal that contains iron
binding ratio of 3:1 which might differ according to the can lower the amount of iron absorbed, whereas
pH of the medium. Additionally, the type of drinking tea before would not. According to the
polyphenol, the ratio of iron to polyphenol, and the available research, healthy people who are not at risk of
presence of ascorbic acid also influence the binding iron deficiency should not be recommended to decrease
ratio[11]. The structure of the polyphenol also has an having tea. For people at risk stage of iron deficiency,
impact on the complex formation. While bidentate it is recommended to consume tea between meals and
polyphenols, like catechin, bind iron through two sites, wait at least one hour after eating. Most research did not
they can be quite potent ligands. In contrast, demonstrate declines in iron status with the use of
monodentate polyphenols, like phenol, have only one tannin-rich meals over time, even though tannin
donor atom to bind to the central iron atom, hence form consumption limits iron bioavailability. According to
weak complexes with the iron [11].The inhibitory the study, those who are at risk of iron deficiency can
action of iron absorption in the presence of polyphenols continue to have tea if they supplement their heme-iron
needs to be researched more, as many parameters are consumption or fortify their meals with iron.
accountable for the total activity. The diet type, age,
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